Leptin-dependent phosphorylation of PTEN mediates actin restructuring and activation of ATP-sensitive K+ channels

Ning, K., Miller, L. C., Laidlaw, H. A., Watterson, K. R., Gallagher, J., Sutherland, C. and Ashford, M. L.J. (2009) Leptin-dependent phosphorylation of PTEN mediates actin restructuring and activation of ATP-sensitive K+ channels. Journal of Biological Chemistry, 284(14), pp. 9331-9340. (doi:10.1074/jbc.M806774200) (PMID:19208634) (PMCID:PMC2666585)

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Abstract

Leptin activates multiple signaling pathways in cells, including the phosphatidylinositol 3-kinase pathway, indicating a degree of cross-talk with insulin signaling. The exact mechanisms by which leptin alters this signaling pathway and how it relates to functional outputs are unclear at present. A previous study has established that leptin inhibits the activity of the phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome 10), an important tumor suppressor and modifier of phosphoinositide signaling. In this study we demonstrate that leptin phosphorylates multiple sites on the C-terminal tail of PTEN in hypothalamic and pancreatic beta-cells, an action not replicated by insulin. Inhibitors of the protein kinases CK2 and glycogen synthase kinase 3 (GSK3) block leptin-mediated PTEN phosphorylation. PTEN phosphorylation mutants reveal the critical role these sites play in transmission of the leptin signal to F-actin depolymerization. CK2 and GSK3 inhibitors also prevent leptin-mediated F-actin depolymerization and consequent ATP-sensitive K(+) channel opening. GSK3 kinase activity is inhibited by insulin but not leptin in hypothalamic cells. Both hormones increase N-terminal GSK3 serine phosphorylation, but in hypothalamic cells this action of leptin is transient. Leptin, not insulin, increases GSK3 tyrosine phosphorylation in both cell types. These results demonstrate a significant role for PTEN in leptin signal transmission and identify GSK3 as a potential important signaling node contributing to divergent outputs for these hormones.

Item Type:Articles
Additional Information:This work was supported by Wellcome Trust Grant 068692 (to M. L. J. A.), Tenovus Scotland, and a Biotechnology and Biological Sciences Research Council Studentship (to L. C. M.).
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Watterson, Dr Kenneth
Authors: Ning, K., Miller, L. C., Laidlaw, H. A., Watterson, K. R., Gallagher, J., Sutherland, C., and Ashford, M. L.J.
College/School:College of Medical Veterinary and Life Sciences > School of Life Sciences
Journal Name:Journal of Biological Chemistry
Publisher:American Society for Biochemistry and Molecular Biology
ISSN:0021-9258
ISSN (Online):1083-351X
Published Online:10 February 2009
Copyright Holders:Copyright © 2009 The Authors
First Published:First published in Journal of Biological Chemistry 284(14): 9331-9340
Publisher Policy:Reproduced under a Creative Commons License

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